What this TAJR685M006RNJ tantalum capacitor is
The TAJR685M006RNJ is a Molded tantalum capacitor from the KYOCERA AVX TAJ series, rated at 6.8 µF with ±20% tolerance and a working voltage of 6.3 V. It comes in an 0805 (2012 Metric) surface-mount package, size code R.
The 7 Ohm ESR (Equivalent Series Resistance) is a key parameter for power-supply decoupling and filtering. A higher ESR means more self-heating under ripple current and less effective high-frequency bypass — for a 6.8 µF cap at 6.3 V, budget the ripple current accordingly to stay within the thermal limits of the 0805 package.